How big is a 3 carat oval diamond?

By HeyGema™ · Updated

In short

A 3 carat oval diamond measures about 11.5 x 7.9 mm. It faces up 6% bigger than a round diamond of the same weight. On a size 6 finger it covers 48% of the width. For the same weight, a round diamond is 9.3 mm.

Carat to mm calculator

About 11.5 x 7.9 mm

An estimate for a well-cut stone. A deep or shallow cut faces up smaller or bigger.

3 ct oval
11.5 x 7.9 mm
3 ct round
9.3 mm
Side by side
3 ct round inside 3 ct oval
A 3 carat oval diamond beside a 3 carat round, to the same scale.

3 carat oval diamond size

A well-cut 3 carat oval diamond measures about 11.5 x 7.9 mm (0.45 x 0.31 inches) at a length-to-width ratio of 1.45:1. It faces up 6% bigger than a round diamond of the same weight. It weighs 0.60 grams.

3 carat oval size by length-to-width ratio

The same weight can be long and narrow or short and wide. These are 3 carat sizes at each ratio. A longer ratio runs the stone along the finger and makes it look slimmer. The face-up area stays almost the same.

1.25:1
Length x width: 10.7 x 8.6 mm
Width on the finger: 52% of a size 6 finger
1.35:1
Length x width: 11.1 x 8.2 mm
Width on the finger: 50% of a size 6 finger
1.45:1
Length x width: 11.5 x 7.9 mm
Width on the finger: 48% of a size 6 finger
1.55:1
Length x width: 11.9 x 7.7 mm
Width on the finger: 47% of a size 6 finger

3 carat oval on a finger

7.9 mm
7.9 mm stone on a 16.5 mm finger: it covers 48% of the widthA 3 carat oval diamond on a size 6 finger.
4
Finger width: 14.9 mm
Oval covers: 53%
5
Finger width: 15.7 mm
Oval covers: 51%
6
Finger width: 16.5 mm
Oval covers: 48%
7
Finger width: 17.3 mm
Oval covers: 46%
8
Finger width: 18.1 mm
Oval covers: 44%
9
Finger width: 18.9 mm
Oval covers: 42%

Oval sizes near 3 carat

2.25 carat
Length x width: 10.5 x 7.2 mm
Round of the same weight: 8.5 mm
2.5 carat
Length x width: 10.9 x 7.5 mm
Round of the same weight: 8.8 mm
3 (this page)
Length x width: 11.5 x 7.9 mm
Round of the same weight: 9.3 mm
3.5 carat
Length x width: 12.1 x 8.4 mm
Round of the same weight: 9.8 mm
4 carat
Length x width: 12.7 x 8.7 mm
Round of the same weight: 10.2 mm

3 carat in other shapes

Every row is a well-cut diamond of 3 carat. The last column is the face-up size against the oval.

Round
Length x width: 9.3 mm
Against oval: -5%
Cushion
Length x width: 8.1 x 8.1 mm
Against oval: -19%
Princess
Length x width: 7.9 x 7.9 mm
Against oval: -13%
Emerald cut
Length x width: 10.1 x 7.2 mm
Against oval: -2%
Asscher
Length x width: 7.9 x 7.9 mm
Against oval: -20%
Radiant
Length x width: 9.4 x 7.2 mm
Against oval: -8%
Pear
Length x width: 12.3 x 7.9 mm
Against oval: -8%
Marquise
Length x width: 15.0 x 7.5 mm
Against oval: +9%
Heart
Length x width: 9.4 x 9.4 mm
Against oval: -22%
Trillion
Length x width: 10.1 x 10.1 mm
Against oval: -18%
Baguette
Length x width: 11.5 x 5.8 mm
Against oval: -7%

Questions

A 3 carat oval diamond is about 11.5 x 7.9 mm at the usual 1.45:1 ratio.
Yes. Face-up, a 3 carat oval is 6% bigger than a 3 carat round (9.3 mm).
There is no rule. The stone is 53% of the width of a size 4 finger and 44% of a size 8. Compare it with a ring you have tried on in the finger chart above.
Yes. A lab grown diamond has the same density as a mined one, so it measures the same for the same weight.

More size charts